Effective 4/00
I.B. 48020
Cutler-Hammer
Instructions for Mechanical Latch Attachment for Type SL Medium
Voltage Vacuum Contactor
DANGER
HAZARDOUS VOLTAGE
Read and understand this manual in its entirety before
installing or operating a mechanical latch or contactor.
Qualified personnel must perform installation, adjustment,
and maintenance of this equipment. A qualified person is
one who is familiar with the construction and operation of
the equipment and who is aware of the hazards involved.
This instruction book should not be considered all-inclu-
sive regarding installation, adjustment, and maintenance
procedures.
Read and understand all instruction literature for the SL
Contactor before performing any work on the contactor or
the latch attachment.
DESCRIPTION
The SL Contactor in its standard configuration is a mag-
netically held device. A mechanical latch attachment can
be added to the standard SL that will maintain the
contactor in the closed position when power is removed
from the main operating coil. A separate unlatch coil must
then be energized to allow the contactor to open.
The unlatch coil is intermittently rated. Control power
should be applied to the coil only long enough to allow the
contactor to open. Two normally open auxiliary contacts
(wired in parallel) on the contactor should be used to open
the circuit to the unlatch coil.
Although the latch (closing) coil is continuously rated,
power should be removed from the coil after the contactor
is closed to insure that the contactor opens when the
unlatch coil is energized. Make certain that the close
pushbutton (or other device) is a momentary device that
will apply power to the latch circuit for a short time only.
Do not use a maintained device which will cause the
contactor to stay closed even after the unlatch coil is
energized. Do not wire a normally closed (NC) auxiliary
contact directly into the coil closing circuit to remove
power from the coil. To do so may result in a failure to
latch since the contact may open before the coils have
been powered sufficiently long enough to fully close the
contactor.
A typical control schematic for a mechanically latched
contactor is shown in Figure 2.
Figure 1: SL Contactor with mechanical latch installed.
Figure 2: Typical schematic for latched contactor
